Telegraphy.



T. A. EDISON.

TELEGRAPHY.

APPLICATION FILED JUNE 20, 1907. 909,877. Patented Jan. 19, 1909.

2 SHEETS-SHEET 1.

9 3 I R. fil l' lgl'l'h a 15222029102:- ZZZ7265; at Q M4 T. A. EDISON.

TELEGRAPHY.

APPLICATION FILED JUNE 20, 1907.

909,877. Patented an. 19, 1909.

2 SHEETS-SHEET 2.

moms A. EDISON, or'LLEwELLYu' PARK RANGE, Nnw'mnsEr' TELEGRAP are.909,877.

specification or Letteim Patent; PatenteIiJan. 19; 1909.

Application filed Juna20, 1907. SerialNmt i'l 9 ,83l).

ToaZZ whom it may "concern;

'Be' it known that I, THOMAS A. Emsorna citizen of the United States,residing at Llewellyn Park, Orange, county of Essex, and State of N ew,Jersey, have invented certain new and useful Improvements in Telegraphy,of which the following is a descriptlon.

My invention relates to improvements in telegraphy and my object isto'provide. an arrangement by which a neutral relay designed 'to beoperated by variations in current strength, will be unaffected byreversals of'current in the circuit in which the relay is included. Sucha situation is presented in connection with the well-known quadruplextelegraph operating either on the bridge or differential principle.IVith such an apparatus at the receiving station and in circuit with theline and with each other are ar-v ranged a polarized relay responsive toreversals of current, and a neutral relay res onsive to variations incurrent strength.

ne of the defects which has always existed in the quadruplex telegraph,or in fact in any other system in which a neutral relay is traversed bya reversed current, is that when the armature of the neutral relay isattracted by the full current strength and a reversal of the currenttakes place, the armature momentarily falls away from the front stopwith the likelihood of producing a kick or false signal in the localsounder. Numerous suggestions have been proposed for overcoming thisdefect, such asarranging the neutral relay to make contact on the backstop, or by arranging an auxiliary magnet which cooperates with thearmature of the neutral relay and receives a momentary charge from acondenser when the current by the change of polarity ceases, to therebyserve to bridge over the interval of no magnetism. The suggestions whichhave been made for overcoming the defect mentioned have not, however, inpractice and on lines of considerable length, been entirelysatisfactory, since in reversing the current through the neutral relaythe magnets thereof when the current ceases, require to be completelydischarged before they can be built up by the succeeding impulse ofopposite polarity, and during this interval the relay armature being nolonger attracted is free to be drawn back to produce a false signal. Bmy invention, I entirely overcome this de ect, since I arrange the.neutral relay in such a way that although thecurrent on the line maybereversed, the current passing through the neutral relay will be'alwaysof the same polarity. Although" the current whichthus traverses theneutral relay will be mome'nta rily weakened during the changes of polarity on, the line, yet, sincethe polarity of the magnets of the neutralrelay is never changed, there is no interval corresponding to that nowencountered when the polarity of such magnets is changed, andfurthermore, the residual magnetism will materially aid in maintainingthe attraction of the armature during the periods in which the currentis momentarily weakened. I find from actual experiments with the apparatus that there appears to besubstantially no movement of the armatureof the neutral relay under the conditions noted, when the currentthrough the same is reversed, while under the old conditions, when-thereversals take place in the relay magnets, the movements of the armaturethereof away from the front stop are quite perceptible.

In carrying the invention into effect I arrangement of rectifiers bywhich, although the current on the line may be reversed, the polarity ofthe current influencing the neutral relay will remain unchanged,

as I will more fully hereinafter describe and claim. The mostsatisfactory rectifier for the purpose, both as to economy ofinstallation and certainty of operation, is the socalled aluminumrectifier, employing an aluminum electrode opposed to an electrode oflead or platinum in a suitable electrolyte. Such a rectifier, as is wellknown, when included in an electric circuit, presents a practicallyperfect insulation to currents of one polarity without appreciablyresisting currents of the opposite polarity. It becomes possible, as Ihereinafter point out, to arrange a number of these rectifiers in such away that currents of reversed polarity'will be so commutated as to passthrough the neutral relay always in the same direction.

.combine with the neutral relay a suitable In order that the inventionmay be better ized relay will not be subjected to the reversals ofcurrent which control the polarized relay, and Fig. 2, a similar view ofa corresponding apparatus operating on the 5 difierential method inwhich rectifiers are employed for commutating the reversals of currentat the neutral relay.

Referring first to Fig. 1, most of the elements are so well-known as torequire no more than a very general description. A pole changer 1, iscontrolled by a magnet 2, from a key 3, in a local circuit. Thetransmitter 4, is controlled by a magnet 5, operated by a key 6, in asecond local circuit. The battery 7, 8, is divided into unequalportions. By reason of the connections shown, the pole changer 1 sendsto the line 9, reversals of current from the battery 7, or the twobatteries 7, 8, in combination, while the transmitter 4 cuts the battery8 in or out of line,

as may be desired. One of the bridge wires -10 leads to the line, andthe other bridge wire 11 to ground, as shown. The circuit 12, whichcompletes the bridge, includes the polarized relay 13, of any usualconstruction, which controls the ordinary sounder in-the usual way, andsaid circuit also includes a t neutral relay 14 of any suitablecharacter, whose armature through asuitable auxiliary relay controls asecond sounder. In the circuit 12 isalso included four rectifiers 15, 15and 16, 16, arranged as shown, the aluminum electrodes thereof beingrepresented as considerably longer than the lead or platimfi'n'electrodes. It will be observed that the circuit after passing thepolarized relay 13 branches and leads to the aluminum electrode of therectifier 15 and to the lead or platinum electrode of the rectifier 16.It 40 will also be observed that the aluminum electrode of the rectifier15 and the lead or platinum electrode of the rectifier 16 are connectedwith the circuit 12 beyond the neutral relay, while the connections tothe neutral relay are between the rectifiers of the 7 two sets. Byreason of this construction, it-

- will be seen that if the current flows along the line 9 towards thepolarized relay 13, as indicated by the arrow A, it will encounter thealuminum electrode of the rectifier 15, which will act practically as aninsulator, so that all the current will pass through the rectifier 16.This current will then encounter the aluminum electrode of the rectifier16, which will oppose it, so that all the current passes in thedirection of the arrow through the neutral relay and thence through therectifier 15" to the line 12. If, however, current passes in theopposite direction, as

shown by the arrow B, it will encounter the aluminum electrode of therectifier 15. and consequently will pass through the rectifier 16 andthence through the polarized relay in the same direction as before,thence through the rectifier 15 and polarized relay to the line. Thus,it will be seen that although the current is reversed on the line so asto actuate the polarized relay, yet no reversal of current takes placeat the neutral relay. Although during the change of polarity, thecurrent in the neutral relay will manifestly be weakened, this effect ismomentarily much shorter than the interval required to discharge andbuild up the magnetism in the neutral relay if the ciirrent werereversed through the same. Furthermore, as I have before pointed out,the residual magnetism of the neutral relay tends materially to hold itsarmature in an attracted position during the momentary 8O periods inwhich the weakening of the current takes place.

Referring now to Fig. 2, I here illustrate a quadruplex apparatusoperating on the differential principle, most of the parts being so wellknown as to require only a very general description. Here there is apole changer 1, operated by a magnet 2, controlled by a key 3, in alocal circuit, and a transmitter 4, operated by a magnet 5, controlledby a key 6, in a'second local circuit, and a battery 7 8, as with thearrangement shown in Fig. 1. From the neutral connection of the polechanger 1, a circuit 17, extends to one of the differential coils 18, ofthe diflerential polarized relay 19. Thence,

the circuit extends through four rectifiers 20, 20, and 21, 21, asshown, and thence to the line 9. The circuit 17 also includes thedifferential coil 22 of the relay 19, and thence extends through fourrectifiers 23, 23 and 24, 24: arrangedas shown, and thence to theartificial line 25. Thedifi'erential neutral relay 26 is arranged sothat its armature on the back stop will control an auxiliary relay 27,which in turn controls a sounder 28 in the usual way. The'main line coil29 of the differential relay is as shown, connected between therectifiers 20, 20' and rectifiers 21, 21', while the artificial linecoil 30 is connected between the rectifiers 23, 23' and 24,

' 24. With this arrangement, as with Fig. 1,

the aluminum electrodes of the rectifiers are illustrated asconsiderably longerthan the lead or platinum electrodes thereof. Inoperation, assuming the current from the distant station to be flowingon the line 9, in the direction of the arrow A, it will be opposed bythe aluminum electrode of the rectifier 20, and will therefore enter therectifier 21, and being opposed by the aluminum electrode of therectifier 21, will flow through the main line coil 29, of the neutralrelay in the direction of the arrows, passing thence through therectifier 20 and the main line coil 18 of the polarized relay. Assumingthat this current is of the full battery strength, the neutral relaywill therefore be operated, while, if of the proper polarity to 1operate the polarized relay, the armature of 130 the latter would beattracted. If,-however,

the current from. the distant station islr e versed and flows in thedirection of the arrow B, it'will be opposed by the aluminum elec--trode of the rectifier 20, and hence will-enter the rectifier 21, so asto traverse the main line coil 29, of the neutral relay in the samedirection as before, and will pass to the line 9, through the rectifierHence, the reversals of the current on the main line will not affect themain line coil 29 of the neutral relay, which, therefore, will never bereversed as to its polarity. A current from the home station flowinginthe direction of-the arrow "B, will-flow equally through the main linecoil 18, and the artificial line coil'22 of the polarized relay, so thatsaid coils will oppose one another, in the usual way. The'c'urrent fromthe main line coil 18 injpassing to the main line '9, will take the samedirection as a before in passing through the main line coil 29 of theneutral relay. That partof the current which traverses the artificialline coil 22 of the polarized relay will enter the rectifier 23 andproceed thence to the artificial line coil 30 of the neutral relay,thereby opposing the coil 29 so as not to affect the neutral relay, andthence through the rectifier 24' to the artificial line 25. Although thecurrent at the home station is reversed, yet, by reason of therectifiers arranged as shown no reversal takes place at the neutralrelay, and consequently, the objection now encountered of the armaturebeing withdrawn when the current is reversed on the main line, will beovercome. It will be-understood, of course, that the arrangements I haveabove described are merely illustrative of my invention, and thatsuitablemodifications thereof will be made in applying the inventioninother connections and in other arts.

Having now describedv my invention, what I claim as new anddesire'tosecure by Let ters Patent is as follows r l. The'combination.with acircuit, and means for impressin thereon currents of varyingstrength an of.;reve'rsed polarity,

of a neutral relay and aseries of rectifiers between the said relayand-said circuit and so disposed as to commutate said lcurrents,

whereby all of said currents will pass through the relay in the same'direction, substantially as and for'the purposes set forth. 2. Thecombination "with a circuit, and

jmeans'for' impressing thereon currents of varying strength and ofreversed polarity,of a neutral relay and a series of aluminum rectifiersbe'tween the said relay and said circuit and so disposed as to commutatesaid currents, whereby all of said currents will pass throu h the relayin the same direction,- iubslgantial ly as and for the purposes; setort.'-

3'. The combination with a neutral relay arranged to make contat on itsback stop,

ofaseries of rectifiers. in circuit therewith therewith and so arrangedas to commutate currents of reversed polarity, whereby all such currentswill pass through the relay always in the same direction, a source ofcurrent and a polarized relay in circuit with said neutral relay, saidpolarized relay being located between said source and said series ofrectifiers, substantially as set forth.

'5.'The combination with a line, a polarized relay and a neutral relayat a receiving station in circuit with the line'and with each other,means for reversing the polarity of current on the line to operate thepolarized relay, and means interposed between the polarized relay andthe neutral relay to com mutate said reversed currents, so thatall ofthe currents will pass through the neutral relay always in the samedirection, substantially as set forth.

6. In a telegraph apparatus, the combina-' tion with the main line, apolarized relay, a neutral relay, .and .means for impressing 10 upon themain line currents of varying strength and of reversed polarity, ofmeans for commutating the currents at the neutral relay,-whereby thecurrent will always influence said relay in the same direction, 'sub-105 stantially as and for the purpose set forth.

7 In a telegraph apparatus, the con bina-' ---tion with the main line, apolarized relay, a

neutralrelay and means for impressing upon the main line currents ofvarying strengths and of reversed polarity, of a series of rectifierscotiperating with the neutral relay and so arranged that any currentsinfluencing the same will always flow in the same direction through theneutral relay, irrespective of their direction on the mainline,substantially as and for the purposes set forth.

8. In a quadruplex telegraph,system,'the combination withthe'maln line,a bridge and means for impressing upon the main 129 line currentsof'varying strength andreversed polarity, of a polarized relayconnectedacross the bridge, four rectifiers in said connection arranged intwosets, and a neutral relay having connections between each set ofrectifiers, substantially as and for the purposes set forth.

Q 9. In a quadruplex telegraph system, the combination with the mainline, a bridge and means for impressing .upon the main line 130 4eee,e77

currents of Varying strength and reversed This specification signed andwitnessed polarity, of a polarized relay connected this 18th day ofJunelQOT. across the bridge, four aluminum rectifiers in saidconnection'arranged in two sets, and 1 THOMAS O .a neutral relay havingconnections between Witnesses:

each set of rectifiers, substantially as and for FRANK 1L. DYER,

the purposes set forth. I ANNA;- R; KLEHM.

